1. Field of the Invention
The present invention relates to an apparatus for manufacturing molten iron by using a calcination furnace, and a manufacturing method therefor. More specifically, the present invention relates to an apparatus for manufacturing molten iron by using a calcination furnace, and a manufacturing method therefor, in which a high temperature reducing gas (1000 to 1100.degree. C.) from a melter gasifier is used as a calcination heat in a calcination furnace so as to cool the high temperature reducing gas to the optimum reduction temperature (800 to 850.degree. C.), and so as to supply the cooled reducing gas to a shaft furnace, whereby the manufacture of the molten iron can be efficiently carried out, and a high thermal efficiency is realized even without a separate gas cooling device.
2. Description of the Prior Art
Generally, the molten iron manufacturing apparatus which utilizes the smelting reduction such as COREX, DIOS, HISMELT or the like which is under study for replacing the blast furnace is equipped with a melter gasifier and a shaft furnace. Thus by utilizing the high temperature reducing gas from the melter gasifier, the iron ore which is filled in the shaft furnace is made to undergo a reduction. Then the reduced iron ore which has undergone the reduction is transferred to a melter gasifier to make it undergo a final reduction.
As shown in FIG. 1, U.S. Pat. No. 4,978,387 discloses a molten iron manufacturing apparatus which uses the ordinary coal. In this conventional molten iron manufacturing apparatus, an iron ore 1a and additives (lime stone and dolomite) 1b are put into a shaft furnace 2, and then the iron ore 1a is made to undergo a reduction by 90 to 95%. Then a melter gasifier 5 is filled with an ordinary coal 3, the reduced iron ore and a calcined additive. Then the ordinary coal is burned within the melter gasifier so as to produce heat and a reducing gas. By utilizing the heat and the reducing gas, the iron ore which has been reduced in the shaft furnace 2 is smelted and finally reduced for the second time. Under this condition, the gas which is produced in the melter gasifier 5 has a temperature of 1000 to 1100.degree. C.
Meanwhile, the reducing gas which is produced in the above described manner is transferred through a generator gas line 6 (which is connected to the melter gasifier 5) to a cyclone 7. The cyclone 7 captures the dusts within the reducing gas, and the high temperature reducing gas is supplied through a reducing gas line 9 to the shaft furnace 2. Meanwhile, the dusts which have been captured by the cyclone 7 are made to return through a dust burner 8 to the melter gasifier 5.
The reducing gas which is supplied to the shaft furnace 2 has to be maintained at a temperature of 800-850.degree. C., and therefore, the hot reducing gas which has been discharged from the cyclone 7 and which has a temperature of 1000-1100.degree. C. has to be necessarily cooled. In order to be cooled, a part of the hot reducing gas which has removed the dusts is transferred through a cooling gas line 10 (which is connected to the reducing gas line 9) to a venturi scrubber 11 so as to be cooled.
The reducing gas which has been cooled by the venturi scrubber 11 is supplied by a compressor 12 to a mixed gas line 13 which is connected to the generator gas line 6 of the melter gasifier 5. Thus the cooled reducing gas is mixed with the hot reducing gas which has been produced in the melter gasifier 5, with the result that the hot reducing gas of 1000-1100.degree. C. is adjusted to the optimum reducing temperature of 800-850.degree. C. The reducing gas which has been temperature-adjusted is finally exactly adjusted to 800-850.degree. C. in the reducing gas line 9 so as to be supplied to the shaft furnace 2. Further, this reducing gas furnishes heat for the reduction of the iron ore 1a and the calcination of the additives (lime stone and dolomite) 1b.
However, in the above described conventional molten iron manufacturing apparatus which uses the ordinary coal, the reducing gas which is produced in the melter gasifier has a temperature of above 1000.degree. C. Therefore, its temperature is adjusted to an optimum reducing temperature of 800-850.degree. C., and then, the reducing gas is supplied to the shaft furnace. For this purpose, a separate cooling device such as the venturi scrubber 11 is necessarily required. Further, if the cooled reducing gas is to be supplied to the mixed gas line 13 which is connected to the melter gasifier 5, a separate pressing and sending device such as the compressor 12 is required, and the compressor is frequently disordered, thereby causing problems.